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A substance is characterized by a burn rate vs. pressure chart and burn rate vs temperature chart. Higher burn rate than the speed of sound in the material (usually several km/s): "detonation" A few meters per second: "deflagration" A few centimeters per second: "burn" or "smolder" 0.01 mm/s to 100 mm/s: "decomposing rapidly" to characterise it.
This graph shows different pressure curves for powders with different burn rates. The leftmost graph is the same as the large graph above. The middle graph shows a powder with a 25% faster burn rate, and the rightmost graph shows a powder with a 20% slower burn rate. Energy is the ability to do work on an object. Work is force applied over a ...
By definition, a "low explosive", such as black powder, or smokeless gunpowder has a burn rate of 171–631 m/s. [15] In contrast, a "high explosive", whether a primary, such as detonating cord, or a secondary, such as TNT or C-4, has a significantly higher burn rate about 6900–8092 m/s. [16]
The first powders were called "MR" for military rifle powder. In the 1920s these powders were improved and the name was changed to IMR. Various different powder are produced and are given numbers to distinguish them. The different types of powder typically have different burning rates.
Gunpowder velocity depends on the amount and type of powder (burn rate) etc. Assuming that the average velocity of the powder gases is half the bullet muzzle velocity, the formula can be simplified to the following:
By manipulation of the shape it is possible to influence the burning rate and hence the rate at which pressure builds during combustion. Smokeless powder burns only on the surfaces of the pieces. Larger pieces burn more slowly, and the burn rate is further controlled by flame-deterrent coatings that retard burning slightly.
A powder burn is a type of burn caused by exposure to the combustion gases which are expelled from the muzzle of a firearm as it is fired. [1] Powder burns only occur when the individual is in close proximity to the discharging firearm, as the gases quickly dissipate. [ 2 ]
The differences in burning rate were achieved by several means. Changes to formulation were altering ingredients relative percentage by weight and using differently processed charcoals for fuel than those of a standard 75:15:10 (potassium nitrate:charcoal:sulfur) black cannon powder.